4D printing of shape memory polymer composites: A review on fabrication techniques, applications, and future perspectives

Shape memory materials

Critical appraisal and systematic review of 3D & 4D printing in sustainable and environment-friendly smart manufacturing technologies

Catalytic ozonation of atrazine with stable boron-doped graphene nanoparticles derived from waste polyvinyl alcohol film: Performance and mechanism

A series of aliphatic polybenzimidazoles (PBIs) with methylene groups of varying length were synthesized by the high-temperature polycondensation of 3,3′-diaminobenzidine (DAB) and the corresponding aliphatic dicarboxylic acid in Eaton’s reagent. The influence of the length of the methylene chain on PBIs’ properties was investigated by solution viscometry, thermogravimetric analysis, mechanical testing and dynamic mechanical analysis. All PBIs exhibited high mechanical strength (up to 129.3 ± 7.1 MPa), glass transition temperature (≥200 °C) and thermal decomposition temperature (≥460 °C). Moreover, all of the synthesized aliphatic PBIs possess a shape-memory effect, which is a result of the presence of soft aliphatic segments and rigid bis-benzimidazole groups in the macromolecules, as well as strong intermolecular hydrogen bonds that serve as non-covalent crosslinks. Among the studied polymers, the PBI based on DAB and dodecanedioic acid has high adequate mechanical and thermal properties and demonstrates the highest shape-fixity ratio and shape-recovery ratio of 99.6% and 95.6%, respectively. Because of these properties, aliphatic PBIs have great potential to be used as high-temperature materials for application in different high-tech fields, including the aerospace industry and structural component industries.

https://www.mdpi.com/2073-4360/15/6/1399/pdf?version=1678519650

Aliphatic Polybenzimidazoles: Synthesis, Characterization and High-Temperature Shape-Memory Performance

Shape memory polymers (SMPs) are among the main groups of smart materials widely used in smart textiles and apparels, intelligent medical devices, sensors & actuators, high-performance water–vapor permeability materials, morphing applications, and self-deployable structures in spacecraft. However, SMPs have some limitations: comparatively low tensile strength and stiffness, relatively low recovery stress, low thermal conductivity, inertness to electrical, light, and electromagnetic stimuli accompanied by slow responsibility and low recovery time during actuation, which often limits SMPs potential applications in high-performance field. In recent years, researchers have focused more on shape memory polymer nanocomposites (SMPNCs) than the classical composites to overcome this limitation of the SMPs, as nanofillers have a large surface area and strong interaction with polymers. This review thoroughly examines the progress in SMPNCs, including the very recent past, with a particular focus on their structure–property relationship. Considering all the SMPs, the most commonly used SMPs like polyurethane, epoxy, polycaprolactam, polylactic acid, and polyvinyl alcohol along with carbon-based (i.e., CNTs, carbon black, graphene oxide, graphene nanoplatelets, graphene quantum dots, nano-diamonds), metal oxide-based (i.e., Fe3O4, TiO2), cellulose-based (i.e., cellulose nanocrystals, nano-cellulose gel), and other nanomaterials like nano-clay, TiN, AuNRs, organic nanoparticles, silica, sepiolite, silsesquioxane, and hydroxyapatite nanofillers are discussed. The future development of SMPNCs may enhance their performance under thermal, electric, light (UV/NIR), magnetic, and solvent (pH/water) stimuli, which may open the door to more advanced applications in the field of aerospace, robotics, sensing and actuation, and biomedical.

Shape memory polymer nanocomposite: a review on structure–property relationship

In this work, a novel UV-curable polyurethane acrylate (PUA) oligomer was developed from castor oil (CO). Reaction monitoring and structures of the PUA oligomer were characterized by Fourier transform infrared (FTIR) and 1H nuclear magnetic resonance (NMR). Subsequently, a series of UV-curable resins were prepared by combining PUA with different reactive diluents, and their effect on thermal and mechanical properties was investigated. From the overall characterization trend, it was observed that the formulation containing trimethylolpropane triacrylate (TMPTA) showed the highest mechanical strength and thermal stability. Whereas the formulation containing isobornyl acrylate (IBOA) showed the least performance, and dipropyleneglycol diacrylate (DPGDA) showed properties ranging between TMPTA and IBOA. Furthermore, incorporating 1% TiO2 into the formulation increases the resin's viscosity and mechanical properties without disturbing its thermal stability. This work offered a simple method to prepare vegetable oil-based high-performance PUA resins that could be used in the 3D printing industry for general-purpose prototyping applications to make architectural models, automotive components, and medical components. 

Haresh Bhanushali

Papers

Shape memory polymer nanocomposite: a review on structure–property relationship

Castor oil‐based UV ‐curable polyurethane acrylate resins for digital light processing ( DLP ) 3D printing technology